Ultraviolet Radiation Induced DNA Damage in Bacterioplankton in the Southern Ocean

9419037 杰弗里现在有强有力的证据表明，紫外线辐射在地球表面的某些地方正在增加。 主要关注的是南极洲和南大洋上空臭氧消耗的年度模式，与臭氧洞事件发生前相比，这些地区的臭氧水平下降了74%。 平流层中臭氧浓度的降低已被证明会导致紫外线辐射水平的增加。 臭氧消耗导致的紫外线辐射增加对浮游植物和初级生产的影响引起了广泛的关注，而对细菌的影响却在很大程度上被忽视了。 从以前在南大洋和其他地方的研究中可以明显看出，细菌在营养物质的矿化中发挥着至关重要的作用，并提供了与高等生物的营养联系。 本研究的目的是确定浮游细菌的DNA损伤造成的紫外线辐射和臭氧消耗的功能，与DNA修复基因（recA）的损伤程度的诱导强度，并估计通过细菌组合的碳通量的压力的影响。 在分子生物学中识别光产物和检查细胞DNA修复机制的诱导的敏感新进展将与测量细菌生物量和生产的传统方法相结合。 嘧啶-嘧啶酮（6-4）和环丁烷二聚体是紫外光辐射产生的独特的光产物。 这些DNA损伤可以使用放射免疫测定法来鉴定。 recA基因在细菌中广泛分布且高度保守。 由于该基因在修复受损DNA中的关键作用，其浓度和活性将被用作细菌对DNA损伤的反应的直接测定。 通过对细菌生物量、产量和生长效率的测量，将估计对细菌碳通量的细微影响。 研究结果将为了解紫外线对植物细胞的损伤程度和修复机制提供依据。 紫外线A辐射和紫外线B辐射都会造成细胞损伤，只有紫外线B辐射会因臭氧消耗而增强。 通过同时分析DNA损伤和recA基因的诱导作为对损伤的一般反应，将紫外线-B辐射的影响与DNA损伤的其他机制进行对比。 将提供关于对总产量的影响的补充资料，并进一步阐明南大洋细菌和浮游植物产量之间的相互作用。

9419037 Jeffrey There is now strong evidence that ultraviolet radiation is increasing over certain locations on the Earth's surface. Of primary concern has been the annual pattern of ozone depletion over Antarctica and the Southern Ocean where ozone levels have declined as much as 74% compared to pre-ozone hole events. Reduction of ozone concentration in the stratosphere has been shown to result in an increase levels of ultraviolet radiation. The impact of increased ultraviolet radiation due to ozone depletion upon phytoplankton and primary production has received extensive interest, while the effects on bacteria have been largely overlooked. It is apparent from previous studies in both the Southern Ocean and elsewhere that bacteria play a vital role in mineralization of nutrients and provide a trophic link to higher organisms. The objectives of this study are identify DNA damage in bacterioplankton resulting from ultraviolet radiation and as a function of ozone depletion, relate the intensity of the induction of DNA repair genes (recA) to the extent of damage, and estimate the effect of the stress on carbon fluxes through bacterial assemblages. Sensitive new advances in molecular biology to identify photoproducts and examine the induction of cellular DNA repair mechanisms will be coupled with traditional approaches for measuring bacterial biomass and production. Pyrimidine-pyrimidone (6-4) photoproducts and cyclobutane dimers are the unique photoproducts created by ultraviolet radiation. These DNA lesions may be identified using radioimmunoassays. The recA gene is wide spread and highly conserved among bacteria. Because of the pivotal role of this gene in repairing damaged DNA, its concentration and activity will be used as a direct assay of the bacterial response to DNA damage. With measurements of bacterial biomass, production and growth efficiency, subtle effects on bacterial carbon fluxes will be estimated. The results will provide information on the amount of UV induced molecular damage and repair mechanisms in planktonic populations. Both ultraviolet-A radiation and ultraviolet-B radiation create cellular damage, while only ultraviolet-B radiation is enhanced as a result of ozone depletion. Through simultaneous analysis of DNA damage and the induction of the recA gene as a general response to damage, the effect of ultraviolet-B radiation will be contrasted with other mechanisms of DNA damage. Additional information will be provided on the effects on total production and further elucidate the interactions of bacteria and phytoplankton production in the Southern Ocean.